1. Field of the Invention
The present invention relates to an optical disk apparatus.
2. Description of the Related Art
There is a possibility that a laser emission device of an optical pickup used in an optical disk apparatus deteriorates or is destroyed due to electrostatic from a worker performing the assembly of optical disk apparatuses, or the like in assembly processes of the optical pickup and of the optical disk apparatus. Hence, in such assembly processes, in order to protect the laser emission device from electrostatic, lead-out conductors connected respectively to the anode and cathode electrodes of the laser emission device in a state of being not connected to a circuit are short-circuited on the lead-out board by connecting them with solder.
Furthermore, for the emission of the laser emission device during adjustment, inspection and the like, performed in the assembly process of the optical pickup, such as the adjustment of the emission intensity of the laser emission device, and the skew adjustment and the positional alignment with the photo detector of an objective lens drive mechanism, the lead-out conductors soldered to each other on the lead-out board need to be unsoldered to open the short circuit between both the electrodes. On the other hand, after the adjustment and inspection, in order to protect the laser emission device, the lead-out conductors are soldered to be short-circuited.
Also in the product assembly process after the optical pickup assembly process, for the emission of the laser emission device during product adjustment, inspection, and the like, the lead-out conductors connected by solder on the lead-out board need to be unsoldered to open the short circuit between both the electrodes.
On the other hand, after the product adjustment and inspection, in order to protect the laser emission device, the lead-out conductors are soldered to be short-circuited. Moreover, in the final process, after connecting a circuit board having circuits for driving an optical disk apparatus mounted thereon to the lead-out board, the lead-out conductors on the lead-out board need to be unsoldered to open the short circuit between both the electrodes, for the emission of the laser emission device.
As described above, in the assembly processes of optical pickups and of optical disk apparatuses, the lead-out conductors on lead-out boards need to be soldered and unsoldered repeatedly.
In recent years, there have been provided optical disk apparatuses capable of recording or playing back both CDs (Compact Disks) and DVDs (Digital Versatile Disks) in the market. Some of optical pickups used in these optical disk apparatuses comprise a laser emission device for CD to emit laser light for recording or playing back CDs and a laser emission device for DVD to emit laser light for recording or playing back DVDs different in wavelength from the laser light for CD. Such an optical pickup is electrically connected to a main circuit board having circuits for controlling the operations of the optical disk apparatus mounted thereon to operate, and is provided with a lead-out board (e.g., a flexible printed board) that serves as an electrical connection link-up between the main circuit board and the optical pickup. On the lead-out board, for the emission of the two laser emission devices, there are provided lead-out conductors electrically connected to the anode and cathode electrodes of each laser emission device.
FIG. 7A shows an example of short circuits between both electrodes of the laser emission device for CD and between both electrodes of the laser emission device for DVD of the optical pickup provided in an optical disk apparatus.
A lead-out board 11 is provided for electrically connecting an optical pickup to a main circuit board (not shown) having circuits for controlling the operation of the optical disk apparatus mounted thereon. A lead-out conductor 12 is connected to one electrode (e.g., the anode electrode) of the laser emission device for CD and led out. A lead-out conductor 13 is connected to one electrode, which is of the same polarity as the one electrode of the laser emission device for CD, (e.g., the anode electrode) of the laser emission device for DVD and led out. A lead-out conductor 14 is connected to both the other electrodes (e.g., the cathode electrodes) of the laser emission devices for CD and for DVD and led out. The lead-out conductors 12, 13, 14 are provided predetermined spaces X1, X2 apart respectively on the lead-out board 11 in the width direction (X direction) crossing the longitudinal direction of the lead-out conductors (Y direction).
The anode and cathode electrodes of the laser emission device for CD are short-circuited by solder extending in the X and Y directions over an area 12A, partial-width part of the lead-out conductor 12, opposite the lead-out conductor 14; over an area 14A, full-width part of the lead-out conductor 14; and over the predetermined space X1 between areas 12A and 14A. Furthermore, the anode and cathode electrodes of the laser emission device for DVD are short-circuited by solder extending in the X and Y directions over an area 13A, partial-width part of the lead-out conductor 13, opposite the lead-out conductor 14; over area 14A, full-width part of the lead-out conductor 14; and over the predetermined space X2 between areas 13A and 14A. That is, both electrodes of the laser emission device for CD and both electrodes of the laser emission device for DVD are short-circuited respectively as above, and thereby become of the same potential and free of the influence of electrostatic. Hence, the deterioration and destruction of the laser emission devices can be prevented. See for example Japanese Patent Application Laid-open Publication No. 2003-228866.
However, in the assembly processes of optical pickups and of optical disk apparatuses, the lead-out conductors 12, 13, 14 on the lead-out board 11 are soldered and unsoldered repeatedly, and hence, may be damaged by solder. Especially when using so-called lead-free solder including no lead, such damage is significant. This is because, as the copper component of solder (Sn(tin)-Ag(silver)-Cu(copper)) increases in concentration from 0.5% to 2%, temperatures of soldering irons rise.
FIGS. 7B and 7C are views showing the lead-out conductors 12, 13, 14 of FIG. 7A having been damaged due to repetition of soldering and unsoldering with lead-free solder in the assembly process of the optical pickup or optical disk apparatus.
When the lead-out conductors 12, 13, 14 on the lead-out board 11 are soldered (FIG. 7A) and unsoldered (not shown) repeatedly, as shown in FIG. 7B, the lead-out conductor 12 has an area 12B, partial-width part, opposite the lead-out conductor 14 peeled off by solder. Furthermore, the lead-out conductor 13 has an area 13B, partial-width part, opposite the lead-out conductor 14 peeled off. Moreover, the lead-out conductor 14 has areas 14B, partial-width parts, respectively opposite the lead-out conductors 12 and 13 peeled off. Thus, the lead-out conductor 12 is partially narrowed in the X direction by area 12B peeled off (the conductor 12 becoming thinner), the lead-out conductor 13 is partially narrowed in the X direction by area 13B peeled off (the conductor 13 becoming thinner), and the lead-out conductor 14 is partially narrowed in the X direction by areas 14B peeled off (the conductor 14 becoming thinner).
If the lead-out conductors 12, 13, 14 on the lead-out board 11 in the state shown in FIG. 7B are soldered and unsoldered further repeatedly, the lead-out conductor 12 has an area 12C peeled off by solder. Furthermore, the lead-out conductor 13 has an area 13C peeled off. Moreover, the lead-out conductor 14 has an area 14C peeled off. Hence, the lead-out conductors 12, 13, 14 are broken in the Y direction, and thus the optical pickup cannot be used.